Motion plates may be used in various optical applications instead of, or in addition to, conventional optoelectronic devices. It is desirable to have capability to move the motion plates by rotation and translation with very fine control.
Since the micro-electro mechanical systems (MEMS) were developed, many applications in MEMS have been developed and used. Micro actuator is the main part of the research and applications in MEMS field. Devices and application using MEMS actuators are developed and used in various fields such as optical communication, display, motion sensor, and medical devices. As the applications of MEMS actuators grow rapidly, the demand on controlling motion plate device increases. It is desirable to have the motion control of the MEMS actuator with many degrees of freedom and simple driving method. Usually, electrostatic, magnetic, piezo, and thermal actuations are widely used in the MEMS industry.
A translational motion only MEMS actuator has been used for phase-only piston-style motion and deformable mirrors. These applications are mainly used for phase adaptive optics applications. A rotational motion of MEMS actuator is also developed for light modulation and MEMS device movements. Most of these motion plates have been controlled to have continuous displacements, which are determined at the equilibrium between electrostatic force and elastic force.
As an example, U.S. Pat. No. 7,036,312 is a good example of thermally controlled MEMS actuator device. Two cantilever actuator by thermally controlled make motion of actuation. Also U.S. Pat. No. 6,914,710 shows an example of electrostatic comb actuators. Comb actuator is one of the most widely used electrostatic actuators. Capacitive force of two different plates with different voltages makes strong attraction force. The electro capacitive force is a source of the force of the electrostatic MEMS actuator. Also, U.S. Pat. No. 6,858,911 shows an example of electromagnetic MEMS actuator. The electromagnetic MEMS actuator comprises a magnetic material, and an electrically conductive coil about the magnetic coil. The coil and the magnetic core can be arranged to generate a magnetic field to move the actuation element. But these actuators have a complicated driving mechanism and control method.
Therefore, the demand on the simple control of the MEMS actuator with higher degrees of freedom and precision has been increased in MEMS industry. The present invention is intended to provide a MEMS actuator device with multiple motions, variable degrees of freedom, low driving voltage, and simple activation mechanism. The MEMS actuator of the present invention can have one degree of freedom rotational motion, one degree of freedom translational motion, one degree of freedom rotational and one degree of freedom translational motion, two degrees of freedom rotational motion, and two degrees of freedom rotational motion and one degree of freedom translational motion, depending on its system configuration.